In the production of small packages of light and fragile bulk material like breakfast cereal it is essential to dose the material into the individual packages fairly accurately, and it is also very important not to crush or fragment the material. As a result the standard method used nowadays doses the material by weight, typically shifting a filling chute to the next package when the weight of the package being filled is what it should be. This procedure is relatively tricky, in particular because the very low density of the material requires extremely sensitive weighing and very accurate flow control.
Recourse has therefore been had to volumetric dosing of the material. The simplest systems ape liquid-dosing arrangements with a piston that pushes the material through a tube in doses determined by the piston stroke. Such an arrangement is extremely rough on the material, crushing it much more than can be tolerated in a foodstuff that must reach the consumer in attractive as well as edible condition. It is generally recognized that for best customer appeal the product must have little or no shake, that is tiny nonflake particles.
Another system has a bin filled with the material and having a floor formed by stationary upper and lower plates sandwiching a slider. The plates have holes that are out of line and the slider has an aperture of the same size and alternately alignable with these holes. Reciprocation of the slider moves its aperture first into alignment with the hole of the upper plate so a dose of the bulk material is taken on, and then into alignment with the hole of the lower plate so the dose is dropped therethrough into a waiting container. While being extremely simple in operation, this system has the disadvantage that it partly cuts and fragments the bulk material. Each time the slider aperture moves away from the upper hole much of the material lying at the plane where the upper slider surface meets the lower upper-plate surface is sheared. As mentioned above this is not permissible when the material being packaged is a flake-type food stuff, for instance cornflakes, as it makes the product substantially less attractive for the consumer.